"Do we see each other?" Biden asked. "Do we see each other for who we are?"

Biden devoted his 27-minute speech to the tension between police and minorities in some communities around the country following the deaths of two unarmed black men in encounters with white officers in Missouri and New York City this summer.

The incidents touched off protests and a national debate over police conduct. Tensions escalated after two New York City police officers were fatally shot last month by a man who suggested in online posts that he was retaliating for the deaths of Michael Brown in Ferguson, Missouri, and Eric Garner in New York. The gunman, who was black, committed suicide.

"Men often hate each other because they fear each other," Biden said, quoting King. "They fear each other because they do not know each other. They do not know each other because they cannot communicate, and they cannot communicate because they are separated."

"We have to bridge that separation ... particularly today between police and the community that exists in some places."

Biden did not mention a weekend incident in which several gunshots were fired from a vehicle speeding by the driveway of his Delaware home. Biden and his wife were not home at the time, and there were no reports of injuries.

Police continue to investigate the incident, which prompted the Secret Service to boost security at Biden's home. New Castle County police spokesman Jacob Andrews said in an email Monday morning that authorities had no additional details to release.

"It really is good to be home," said Biden, who left immediately after speaking to a crowd of about 200 people in a half-filled ballroom on Wilmington's riverfront.

Secret Service spokesman Robert Hoback said Sunday that the shots were fired near Biden's home at about 8:25 p.m. Saturday on a public road outside the home's secure perimeter. Biden's home is several hundred yards from the road. Secret Service personnel stationed at the top of the long, winding driveway leading to Biden's home heard the shots, saw the vehicle drive past the home at a high rate of speed and flee the scene.

The shooting occurred just days after the Delaware National Guard increased security at its air base near Wilmington after several incidents in which vehicles approached the main gate before turning around. In several instances, the vehicle occupants appeared to be lost and asked for directions.

The National Guard base is part of a dual-use facility that includes New Castle Airport and which has been used by Biden when he travels to Delaware aboard Air Force Two.

The Bidens spend many weekends at their Delaware home, and, while he served in the Senate, Biden frequently made a daily commute from Delaware to Washington by train.

Biden's speech came just days after a rally in support of police drew about 300 people to downtown Wilmington. Even as the rally was being held, police were involved in a shooting that left a man in critical condition. Authorities said an officer returned fire after the man shot at police following a traffic stop. Police have released few details about Thursday's shooting, including the race of the officers and the occupants of the vehicle.

"Cops have a right to go home at night to see their families," Biden said. "All minorities, no matter what the neighborhood, have the right to be treated with respect, and with dignity."